code: def stem(inputs: tf.Tensor) -> tf.Tensor:
      """Construct Stem Convolutional Group
      :inputs: the input vector
      """
      x = Conv2D(
          16,
          (3, 3),
          strides=(1, 1),
          padding="same",
          use_bias=False,
          kernel_regularizer=l2(WEIGHT_DECAY),
      )(inputs)
      x = BatchNormalization()(x)
      x = ReLU()(x)
      return x
  
file_path: neural-structured-learning/research/third_party/denoised_smoothing/models/resnet20.py
imports: from typing import Union
  import tensorflow
  from tensorflow.keras import Model, Input
  from tensorflow.keras.layers import Conv2D, Dense, BatchNormalization, ReLU, Add, AveragePooling2D, GlobalAvgPool2D
  from tensorflow.keras.regularizers import l2
label_desc: Use image node_id 1 for calling a global function with example usage: stem(inputs) and returns: x